JPH04233473A - Multimeter having at least three input connecting parts - Google Patents

Abstract

PURPOSE: To prevent an operator from connecting an input circuit given to the operator to a measurable characteristic value, which is not set by a measurement area switch, by mistake, by using the single measurement area switch which can be switched by transmitting of a slight force to a measuring system. CONSTITUTION: An interruption prohibition link SK has one cutout part 3 which selectively frees input connection parts 2a-2c in accordance with setting of a measurement area switch S. When the switch S is set to a measurable characteristic value B, the link SK frees only the input connection part 2b at the position of the switch. When the switch S is further rotated in a clockwise direction and set to a measurable characteristic value C, the link SK turns accordingly and frees the input connection part 2a. The cutout part 3 is a long and narrow hole and offsets a positional shift brought about from the input connection part 2a to the input connection part 2c set on a line when the link SK turns.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION The present invention relates to a multimeter of the type defined in the preamble of claim 1.

0002

[Prior Art and its Problems] Multimeters are versatile among measuring instruments and can be used in many different ways in laboratories and factories, as well as among amateur researchers. is highly prized. The range of measurable characteristic values covered by a large number of measuring instruments ranges from voltage to frequency through current, resistance and level, to name a few. Many of the measurement circuits required to detect different measurable characteristic values are very different. This means that different measurable characteristic values require completely different measuring input circuits.

However, for all their versatility, multimeters also have some risks. Therefore, before each measurement, it is important to connect to the correct input circuit for the characteristic value to be measured. For example, if you were trying to measure the mains voltage and accidentally left the input circuit for current measurement switched on, this would have a serious effect on the multimeter, and in the unlikely event that the main fuse suddenly Failure to do so may result in a serious accident for the person taking the measurement. Multimeters typically have internal fuses that are not sufficient to isolate the multimeter from high-voltage power because the arc that occurs when the fuse blows bridges the internal fuse.

Similar problems and dangers to the test object, the multimeter, and the operator arise when another combination of measurable characteristics is applied to the wrong input circuit. Indirect hazards always occur even when operator errors do not result in direct hazards. For example, if the multimeter's display shows that there is no voltage to test because the input circuit happened to not be connected to the measurement system. Operators often perform dangerous operations due to overconfidence in the indication that there is no voltage applied.

[0005] In order to prevent such erroneous operation from occurring with a multimeter, precautions to be taken will vary depending on the structure of the device. In many multimeters, each input circuit has a first input connection common to all input circuits and a second input connection corresponding to each measurable characteristic value assigned to a particular measurement circuit. ,have. Generally, a plurality of measurement ranges are provided for each measurable characteristic value, for example, measurement ranges of 1, 3, 10, 30V, etc. are provided for the measurable characteristic value "voltage." In this case, the input circuit has a voltage divider, by means of which all the voltages are divided into several values or amplified by amplification, so that the appropriate value for the measurement system is available.

A measurement range switch is used to switch a voltage divider to a desired voltage measurement range or to switch a shunt to a desired current measurement range. When operating the measuring instrument, care must be taken that the measuring range switch is set to the value of the measurable characteristic to be measured. At the same time, it is necessary to ensure that the measuring conductor is connected to the correct input connection and therefore to the correct input circuit on the input side of the multimeter.

[0007] If the work is not done very carefully,
Particularly when operated by unskilled persons, it is often the case that one of the two operating movements is forgotten and therefore the wrong input circuit is connected or the wrong measuring range is switched on. be.

[0008] Of course, attempts have been made to attach additional safety devices to limit the risk of erroneous operation. The protection circuits used included passive and active relay switches, controlled semiconductor switches with transistors and thyristors, and fusible links with special construction. Despite the sometimes very high research costs, conventional technology has never been able to safely turn off the high-voltage power switch in the case of a mistake in a very small interior space, such as in modern multimeters. I can't do it. Therefore, the only way to eliminate this risk is to virtually eliminate erroneous operations.

Attempts have been made to solve this problem by replacing the repositioning of the measuring conductor by switching the input circuit. This made the instrument a little easier to operate, but it did not eliminate the problems. The switching of the input circuit is therefore carried out by means of an auxiliary input circuit switch or even by being replaced by a measuring range switch. The auxiliary input circuit switch merely moves the problem elsewhere, and the input circuit switch and measurement range switch must still be set with equal care to the characteristic value of the measurable being investigated. . On the other hand, having all the switching functions in the measuring range switch means that it must be able to switch not only very small but also large amounts of power, which ultimately increases the cost of this component. This will result in an increase in Furthermore, it must be noted that the resulting reduction in the number of operating parts does not necessarily make operation substantially safer. This is because if even one switch is set incorrectly, it will always lead to the wrong input circuit, with certain consequences. In this sense, the need to accurately set the two operating components leads to the need for even more careful operation.

0010

SUMMARY OF THE INVENTION It is an object of the invention to provide a multimeter according to the preamble of claim 1 with a single measuring range switch which can be switched by transmitting a very small force to the measuring system. To provide a multimeter that prevents an operator from accidentally connecting an assigned input circuit to a measurable characteristic value that is not set by a measurement range switch. This object is achieved by the features of claim 1. Preferred details and refinements of the subject matter of the invention are set out in the subclaims.

According to the invention, one interrupt-disabling device is associated with each switch setting of the measuring range switch, so that in each case only one specific input connection is connected. Input connections can be disabled for making contacts that receive test signals. The measurable characteristic value applied to the input connection corresponds as a result of the combination to the measurable characteristic value set with the measuring range switch. The combination to the measuring range switch can be done mechanically or electrically. In either case, the user is protected against accidentally switching to one input circuit for one measurable characteristic value other than the one selected with the measurement range switch. This substantially increases the safety in use of the measuring device.

[0012] An interrupt disabling device of very simple construction can be achieved by mechanical means. That is, there is provided one interrupt-protection link connected to the measuring range switch, so that when the measuring range switch is actuated, its position relative to the input connection changes so that the contact, preferably made as a plug, of the measuring conductor Prevent a component from making a connection to a particular input connection. A rigid connection between the measuring range switch and the non-interruptible link provides a substantial safety benefit in this respect. This is because when the measuring conductor is connected, the inserted plug fixes the interrupt protection link in its position and the measuring range switch is therefore also protected from accidental switching by this coupling part. Therefore, the user must always remove the plug before switching to another measurable characteristic value, thus disabling the interrupt-disabled device. Opening the input circuit ensures that switching only takes place in the de-energized state, so that no current flows that could endanger the contacts of the switch. Only after the changeover is a connection made to the input connection. The measurable characteristic value selected with the measurement range switch is applied.

The interrupt prevention link is made of insulating plastic and is arranged as a contact of the socket in such a way that it can block the receiving channel of at least one input connection made transversely to the plug-in direction. It will be destroyed. There are many variations in the design details of mechanically acting interrupt disabling devices, and it is not possible to list them all here. The disable link should always correspond to the type and construction of the measuring range switch, so preferably a rotating or sliding link is used. A cutout is provided in the interrupt-protection link, positioned according to the switch setting of the measuring range switch, which cutout accepts the input connection assigned to the measurable characteristic value set with the measuring range switch. Keep the groove open all the time.

Furthermore, in a recess provided for receiving and mounting the link in the cover wall of the housing, provision is made for this link to be movable in the area of the input connection. In such a situation, the interrupt disable link can be acted upon by manually moving the actuating part of the measuring range switch and changing its position to a position corresponding to the input connection.

The measuring range switch and the disable link are combined in a suitable manner, ie the actuating part of the measuring range switch is coplanar or parallel to the disable link made as a rotatable part. on the top to ensure that they are joined by a joining part. By suitable means, it can be ensured that this forced connection with the interrupt-protection link takes place only in some areas of the rotation movement performed by the switching part.

The aim is to ensure that a rigid connection to the disable link does not occur over the entire rotation area of the measuring range switch, so that the same measurable characteristic value can be achieved without any change in the position of the disable link. The purpose is to be able to switch to another measurement range.

One switch wheel on the actuating part has at least one tooth which in turn engages another tooth on the rotatable anti-interruption link, preferably as in a Geneva movement. , joins into the groove of the bifurcated fork.

[0018] In order to release the input connection, the cutout provided in the interrupt-disable link must be provided in a position corresponding to that of the input connection that is to be switched on. In a non-interruptible link designed as a rotatable disk, this cutout can be a round hole if the input connection is provided in the form of an arc. On the other hand, if this input connection part is arranged on a straight line as is generally seen, this cutout part is made into an elongated hole so as to offset the positional deviation caused by rotation.

A one-piece interrupt-protection link with appropriate cutouts can be assembled from a plurality of interrupt-protection slides into a single interrupt-protection link. In this case, these non-interrupting slides are each mounted as follows: by means of a cam-shaped slide actuated by a measuring range switch, against the force of a spring holding one slide in its rest position. Move this one slide to move the input connection section to the interrupt-prohibited position. The actuating part of the measuring range switch can act on a cam-shaped slide by movement or rotation.

The electrically actuated interrupt disabling device is configured such that at least one of the input connections, preferably made as a socket contact, is electromagnetically actuated and disables contact. It has one interrupt-disabled component provided so that it can take a position. For example, if the characteristic value of the measurable set in the measuring range switch does not match the characteristic value of the measurable applied to the input connection, the receiving groove of the socket contact is blocked. In this case, too, it is necessary to combine an electromagnetically actuated interrupt-protection component with the measuring range switch, and this is achieved by providing a switching circuit that transmits via the switching part of the measuring range switch.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS There are various means for connecting a measuring range switch to a mechanically acting interrupt disabling device, the first of which is shown in detail in FIGS. Cover plate 21a of multimeter housing 20
In the area shown are a display 28, a plurality of operating elements 29, a measuring range switch S and input connections 1, 2a to 2c. The interrupt inhibiting link SK associated with the measuring range switch S is shown in broken lines in FIG.
This is because it is inside and cannot be seen from the outside.

Details of the measuring range switch S, more precisely of its actuating part 5, are shown in the parts diagrams of FIGS. be. The operating part 5 of the measurement range switch S is an annular switch wheel 5a and a switch twist knob 5.
b, a first coupling part 5c made as a stud;
and a switch blade 5d, which blade serves as a contact carrier plate (not shown) of the measuring range switch.
Acts as a drive unit. This switch blade 5d is
Switch twist knob 5 used as a raised part for operation
b is connected to the switch wheel 5a. A stud-shaped first coupling portion 5c formed on the switch wheel 5a connects the second
The coupling with the coupling portion 25 is performed.

[0023] This coupling device functions in a one-arm Geneva-type operation mode, and has two forked forks 25a, 25b.
This fork forms a guide groove 25c for receiving a tad-shaped first coupling portion 5c. If the selected angle is exceeded while the switch wheel 5 is being rotated, the stud-like first coupling portion 5c will come off the guide groove 25c and the connection between the two parts will be broken. . In this area, the measuring range switch S can be turned further to set another measuring range, usually with the same measurable characteristic value, while the interrupt-protection link SK remains in its final position. switch car 5a
By simply turning the switch in the opposite direction, the first coupling part 5c can be returned and coupled to the second coupling part 25, and the interrupt disabling link SK can be moved at least to the next switch setting position.

In the embodiment of FIG. 1, the measuring instrument has input connections 2a, 2b, 2c, each assigned to a measurable characteristic value A, B, C, and an input connection for all three input connections. It has a common contact point 1. The interrupt-protection link SK has a cutout 3, which selectively releases the input connection 2a or 2b or 2c according to the switch setting of the measuring range switch S. Assuming that the measuring range switch S is set to the measurable characteristic value B, in this position the interrupt disabling link SK releases only the input connection 2b. If the measurement range switch S is turned further clockwise to reach the measurable characteristic value A, the interrupt disabling link SK rotates correspondingly and releases the input connection 2a. This cutout 3 is in the form of an elongated hole and compensates for the positional deviation that occurs when the interrupt inhibiting link SK rotates with respect to the input connections 2a to 2c provided in a straight line. As long as the input connection parts 2a to 2c are provided in an arc shape with respect to the attachment point of the interrupt prohibition link SK, a circular cutout part with an appropriate diameter may be used.

[0025] The interrupt prohibition link SK is attached to the stud 24.
installed by. This stud is cover plate 2
1a, and engages with the mounting hole 33 of the interrupt prohibition link SK. Also, the actuating part 5 is mounted on the cover plate 21a, but from the outside. Starting from the side where the coupling part 5c, 25 is located, the interrupt protection link SK extends to the interrupt protection plate 26, in which the cutout 3 is connected to the input connection 2a, 2b, 2c made as a socket contact 4. It is provided so that it slides on top of the receiving groove 4a and always releases only a specific receiving groove 4a. Inside the housing, the anti-interruption link SK is further protected by a cover 27 that covers the recess 22. The dimensions of this recess 22 are determined by the dimensions of the interrupt prevention link SK and its rotation angle.

As shown in FIGS. 7 to 9, an interrupt prevention link SK associated with the measuring range switch S is configured to provide a specific input connection 2a to 2c for the contact connection of the measuring conductor.
Many solutions can be considered as to how to prohibit or release. In FIG. 7, the interrupt-disabled link S
K is constructed with the help of three anti-interruption slides SS1 to SS3, each of which is held in an anti-interruption position with the help of a spring FE and from which position it can only be moved by a cam-type slide NS; A release position can be reached. In this figure, the cam-type slide NS
Accordingly, cutout section 3 of interrupt-prohibited slide SS2
has released the input connection 2b. This input connection part 2b
is assigned to the measurable characteristic value B of the measurement range switch S.

The mode of action of the interrupt prevention link in FIG. 8 is the same as that in FIG. 7, in which the cam-shaped slide NS is driven only by the linearly moving measuring range switch S, which is provided as a sliding switch. It is not driven by a rotatable measuring range switch S, as in .

In the example shown in FIG. 9, the actuating part associated with the measuring range switch S is not attached to the operating surface of the housing of the measuring instrument, but is attached to its side. In this case, a particularly simple form of an interrupt-protection link is used. This is because the linear movement directly corresponds to the linear arrangement of the input connections 2a to 2c.

In the embodiment shown in FIGS. 10 and 11,
Disabling of certain input connections 2a, 2b takes place with the aid of electromagnetically actuated safety catches R. Figure 1
0 is the measuring range switch S and two auxiliary circuits H1, H2
, and these circuits are respectively provided with magnetic positioners M1, M2, which correspond to the contact connection of the measuring conductor L2 to the plug ST2 by means of safety catches R1, R2. Input connections 2a, 2b can be prohibited. In this figure, the measuring range switch S has one auxiliary switch section S1 which, according to the selection made by the measuring range switch S, is assigned to the measurable characteristic value B and at the same time assigned to the input connection 2a. and connects the auxiliary circuit H1 to the voltage source U, thus activating the magnetic positioner M1 and connecting the input connection 2a to the safety catch R.
1 prohibits. Starting from the test object Q, shown as a voltage source, measuring conductors L1, L2 with plugs ST1, ST2
contacts the common input connection 1 and the input connection 2b assigned to the measurable characteristic value B1, thus input circuit b
can be closed. a measuring range network N connected to the measuring range switch S and adapted in shape and structure to the characteristic values of the particular measurable;
via which the test signal reaches a measuring system Z for evaluation and display of the test signal. After switching the measuring range switch S to the measurable characteristic value A, the magnetic positioner M1 pulls the corresponding safety catch R1 back to the starting position and releases the input connection for the measurable characteristic value A, while the second 2
magnetic positioner M2 is actuated and inhibits the input connection 2b by means of the second safety catch R2.

FIG. 11 shows an input connection 2a, 2b made as a socket catch 4 with a safety catch R, which is actuated by a magnetic positioner M to open the receiving groove 4a of the socket contact 4. closed to one contact that is

[Brief explanation of the drawing]

FIG. 1 is a top view of a multimeter with a rotatable interrupt-disable link according to one embodiment of the invention;

[Fig. 2] Fig. 2 is a cross-sectional view taken along line II in Fig. 1;

[Figure 3] Figure 3
is a plan view showing the switch components taken out from FIG. 1;

FIG. 4 is a cross-sectional view taken along line III-III in FIG. 3;

FIG. 5 is a plan view showing the rotatable interrupt-disable link of FIG. 1;

[Fig. 6] Fig. 6 is a side view of Fig. 5;

FIG. 7 is a plan view illustrating an actuation mechanism of a disable link with individual disable slides according to another embodiment of the present invention;

FIG. 8 is a plan view of a measuring range switch as a slide switch with a plurality of interrupt-protection slides as interrupt-protection links according to a further embodiment of the invention;

[
FIG. 9 is a plan view of a measuring range switch as a slide switch with one interrupt-disable link according to yet another embodiment of the invention;

[Fig. 10] Fig. 10 is a wiring diagram system diagram of a measurement range switch with an electromagnetic interrupt disabling device;

FIG. 11 is a schematic diagram showing a socket contact with an electromagnetically actuated safety catch.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1, 2a-2c... Input connection part, 3... Cutout part, 4... Socket contact, 5... Operating part, 5a... Switch wheel, 5b... Switch twist knob, 5c... First coupling part, 5d
...Switch blade, 20...Housing, 21a...Cover plate, 22...Recess, 24...Mounting stud, 25...
Second coupling part, 25a, b... elongated fork, 2
5c...Guide groove, 26...Interruption prevention plate, 29...Operation parts, 33...Mounting hole, A, A1, A2...Measurement range, A,
B, C, D...Measurable characteristic values, FE...Spring, H1, H
2...Auxiliary circuit, L1, L2...Measurement conductor, M1, M2...
Magnetic positioner, N...Measuring range network, NS...
Cam type slide, Q...Test object, R...Interruption prohibition device, R1, R2...Safety catch, S...Measurement range switch, S1...Auxiliary switch section, SK...Interruption prohibition link or switch link, SS1~3...Interruption Prohibited slide, ST1, ST2...Plug, U...Voltage source, Z
...Measurement system, b...Input circuit.

Claims (13)

[Claims] 1. One measurable characteristic value (A ~C), at least one of the conductors is connected to another input connection (1, 1,
2a to 2c), a measuring range switch (S) that can be moved to one switch setting position corresponding to the selected measurable characteristic value (A to C); In a multimeter with a multimeter, there is an electrically and/or mechanically actuated interrupt disabling device (R, SK) combined with the measuring range switch (S), by means of which the measuring conductors (L1, In order to receive one test signal via L2), the measurable characteristic values (A to D) corresponding to the measurable characteristic values (A to C) set by the measurement range switch (S) are applied. at least three input connections, characterized in that interrupts are disabled for specific input connections (1, 2a to 2c) such that connection is possible only to input connections (1, 2a to 2c) that are Multimeter with parts. 2. The interrupt disabling device (R, SK) is made as an interrupt disabling link (SK) and is connected to the measuring range switch (S), the measuring range switch (S)
When operated, its position changes with respect to the input connection part (1, 2a to 2c), and as a result, the measurement conductor (L
1, L2 ), preferably the plug (ST1, ST2
) with a contact part made as a specific input connection (
1, 2a to 2c), and
With the measurement conductors (L1, L2) connected, switch the measurement range switch (S) to another measurable characteristic value (A~
Make it impossible to switch to the measurement range of C).
The multimeter according to claim 1, characterized in that: 3. The anti-interruption link (SK) is made of an insulating material and connects the receiving groove (4a) of at least one input connection (1, 2a to 2c) made as a socket contact (4) with a plug. As long as the above-mentioned interrupt-disable link (SK) is in the interrupt-disable position with respect to the corresponding input connection section (2a to 2d), the plug (ST1, ST2) is connected to its input connection. 3. The multimeter according to claim 2, wherein the multimeter is configured such that it cannot be inserted into the multimeter. 4. The disable link (SK) is provided depending on the shape and structure of the measuring range switch (S), preferably one rotating or sliding link is used,
At least one cutout (3 ) is provided in said interrupt prevention link (SK), the position of which corresponds to the switch setting position of the measuring range switch, in which position said cutout (3 ) connects to the socket contact ( 4) of one of the receiving grooves (1, 2a to 2c) made as
4a), which is the measuring range switch (S).
4. The multimeter according to claim 1, wherein the multimeter corresponds to the measurable characteristic values (A to C) set in ). 5. The anti-interruption link (SK) is located in the wall (21) of the housing, preferably in a recess (22) provided for receiving and mounting it in the cover plate (21a) of the housing (20). Input connection inside (
1, 2a to 2c), the manually actuated part (5) of said measuring range switch (S), preferably one combined switch wheel (5a), is arranged movably in the area of said non-interruption link ( 5. Multimeter according to claim 1, characterized in that the link changes its position corresponding to the input connection (1, 2a-2c). 6. The actuating part (5) of the measuring range switch (S) is provided on the same plane as the interrupt prevention link (SK) made as a rotating part or on a plane shifted parallel to it, and are coupled to each other by coupling portions (5c, 25) respectively provided to the operating portion (5) and the interrupt inhibiting link (SK), and the forced coupling of the interrupt inhibiting link (SK) is performed to the operating portion (5). Multimeter according to any one of the preceding claims, characterized in that the rotational movement of the multimeter is carried out in at least one partial area. 7. The switch wheel (5a) has a first coupling part (5c), preferably at least one stud, with which a rotatable anti-interruption link (S
Claim 1 characterized in that at least one second coupling part (25) of K) can be coupled with its bifurcated fork, preferably with a Geneva movement.
The multimeter according to any one of 6 to 6. 8. The stud (5c) of the switch wheel (5a) is connected to the guide groove (25c) of the fork (25).
), and the fork (25) is constructed in such a way that it can be slid into the groove and slid out of this groove again in the opposite direction of rotation. multimeter. Claim 9: This forced connection is performed by the switch wheel (5).
The above stud (5) is
c) is removed from the guide groove (25c), the rotary wheel (5a) can further rotate freely to one stop position that limits the rotation range, while the anti-interruption link (SK) remains intact. 9. A multimeter according to claim 1, wherein the multimeter remains in a rest position. , a plurality of measurement ranges (A, A1, A2
) are assigned to the same input connection (2a), the free-rotating part of the switch wheel (5a) relative to the interrupt inhibiting link (SK) is always provided. A multimeter according to any one of claims 1 to 9. 11. The interrupt inhibiting link (SK) has one cutout (3) made as an elongated hole;
As a result, the input connection parts (2a to 2c
) to offset the positional deviation that occurs during rotation, and its input connections (2a to 2c) can be placed at any connection.
The multimeter according to any one of claims 1 to 10, characterized in that the multimeter always releases. 12. An anti-interruption link (SK) consists of individual anti-interruption slides (SS1 to SS3), which can be brought into rest position by one cam-type slide (NS) actuated by a measuring range switch (S). Claim 1, characterized in that by moving it against the force of a retaining spring (FE), it can be moved into a position in which interrupting of the input connections (2a to 2c) is inhibited.
The multimeter according to any one of 11 to 11. 13. At least one of the input connections (1, 2a to 2d), which is preferably made as a socket contact (4), has one interrupt-protection component (R1, R2), which is preferably actuated electromagnetically. , this means that the measurable characteristic value set with the measuring range switch (S) is connected to the input connection (
2a to 2d) assigned to the measurable characteristic values (A to 2d)
D), preferably by blocking the receiving groove (4a), the magnetic Actuation is performed in at least one switch section (S) of the measuring range switch (S).
13. Multimeter according to any one of claims 1 to 12, characterized in that it is commanded by: 1).